Starter for engines



July 6 1926.

- 1,591,832 M. B. JACKSON STARTER FOR ENGINES Filed July 8 1925 Patented .luly e, teas.

est.

MAUNSELL B. JACKSOBLOF TORONTO, ONTARIO, CANADA.

sraarnn son ENGINES.

Application filed July 8,

This invention relates to starters for internal cornbustionengines, and more particularly to that type in which a starter pinion is threaded. on a starter shaft for axial movement thereof. Heretofore it has been thegeneral practice to form a short or small pitched thread on the starter shaft whereby the force tending to move the pinion axially of the shaft is greater than the force tending to move the pinion rotarily on the shaft so that-the pinion is easily moved, due to inertia, along the shaft into mesh with a gear on the engine. This, short pitch had a dis.- advantage in that when the teeth of the pinion and the teeth of theengine gear met end to end, the axial force being greater than the rotary force, the pinion often did 7 not turn andan axial jam resulted which damaged the teeth on both gear and pinion. To remedy this axial, jam a yielding flexible drive' was devised whereby the pinion was not driven directly from the starting motor shaft but was usually threaded on a loose sleeve which was in turn driven from the motor shaft by a spring or some such device. This made the axial jamming less frequent though it did not eliminate it entirely but it hadthe disadvantage of necessitating the turning down of the shaft and consequentweakening of it just where strength was most wanted. The yielding flexible drive construction isexpensive to manufacture and assemble and very liable to get out of order.

Long pitched threads on'the starter shaft have been used to overcome the above objectionable features but, with this type of thread, the pinion has a tendency to slide along the shaft, due to road jars or on going down a steep grade, and mesh or contact with the engine gear when the latter is running. The objects of the present invention are to overcome the objectionable features of both types of starter and to provide a simple starter which may be cheaply manufactured and yet be durable and efiicient.

I attain my object by means of the con- 1 structions hereinafter described and illustrated in the accompanying drawings in. which Fig. 1 is a side elevation of the starter shaft, the starter motor casing being partly shown in section;

1925. Serial No. 42,324.

Fig. 2 a side elevation of the shaft showing the pinion in its inoperative position;

. lfig. 3 a similar view showing the pinion 111 its operative position;

Fig. 4 an end elevation ofFig. 3; and

Fig. 5 a section of the starter pinion.

In the drawing like. reference numerals indicate corresponding parts in the different figures.

B is an extended armature shaft of an electric motor G (only partly shown). This shaft is provided with a long pitched double or triple thread on which a pinion A is screw threaded. On the end of the shaft remote from the motor is slidably mounted a sleeve C which is counterbored to provide clearance for the threads on the shaft B and to form a shoulder 0 adapted to engage the ends of the threads to limit the axial movement of the sleeve in one direction. A casing H is provided with an opening adapted to receive the turned down threaded end 5* of the shaft B and a nut is threaded on this end to secure the casing on the shaft. The casing has a telescopic fit on the sleeve C to exclude dust and dirt from the interior of the former in which a spring D is carried. This spring is disposed on the shaft B and engages the end of the casing and the sleeve to tend to position the shoulder c in engagement with the ends of the threads on the shaft B.

The pinion A is adapted to be meshed, by means of the spring D as hereinafter described, with a gear E connected with the crank shaft of an engine (not'shown), the common practice being to secure the gear to the engine flywheel. The entering ends of the pinion teeth are tapered off as shown to facilitate the meshing of these teeth with the teeth of the flywheel gear, it is adapted to engage the resilient fingers f formed on a disk F which butts against a shoulder b on tie starter shaft B. These fingers limit the axial movement of the pinion, see Fig; 3, to form a rotary drive connection between the pinion and shaft whereby the flywheel gear will be rotated to start the engine.

The pinion is returned to its inoperative position, when the engine is started, in the following manner. The speed of the flywheel gear when operated by the starter motor is less than its speed when the engine is started so that the instant the engine starts, the speed of the starter pinion, relative to the starter shaft, is increased. This causes the pinion to be threaded on the shaft to move it out of mesh with the gear.

To prevent the pinion from accidentally sliding along the shaft, due to road jars or when travelling down inclines, and meshing with or contacting against the side of the gear E I releasably retain the pinion in its inoperative position by the following means. The thread or threads on the shaft 13 are reduced in width, adjacent the sleeve C, to form shoulders is adapted to engage the ends k of the pinion threads. As the pinion is being rotated and axially moved along the shaft B, away from the gear E, it engages the sleeve C and compresses the spring D. hen the ends is of the pinion thread pass the shoulders I: on the shaft thread the pinion revolves on the shaft to bring the ends 70 in axial alinement with the shoulders 7c and the spring I) tends to hold the ends lb' in engagement with the shoulders L. In other words the threads on shaft B are cut away as indicated at Z) and Z1 and the edges a and a of the threads on the pinion are in engagement with the edges and D of the shaft B when the pinion is being axially moved on the shaft. When the ends 70 pass the shoulders 70 the edges a and a of the pinion teeth revolve relative to the shaft teeth and contact with the edges 7) and 6 The edges (0' and a are thus drawn away from the edges Z) and b as shown in Fig. 2.

hen the motor G is again energized to start the engine the shaft B rotates relative to the pinion, due to the inertia of the latter, which disengages the ends 70 of the pinion from the shoulders la and permits the spring D to axially move the pinion to mesh with the gear. If the teeth of the pinion and gear meet end to end the former is slightly rotated on the shaft until they are in position for meshing which is accomplished by the spring. This arrangement of using a long pitched thread and a spring prevents any jamming of the ends of the pinion and gear teeth which would occur if a short pitched thread, adapted to axially move the pinion solely by inertia, was used.

\Vhen the pinion teeth have started to mesh with the flywheel teeth the shoulder 0 en sages the ends of the teeth on the shaft and limits the axlal movement of the sleeve. The gear E tends to prevent rotation of the pinion so that the shaft is threaded through the pinion to fully mesh the latter with the gear.

IVhat I claim is:

1. In a starter for use with an internal combustion engine having agear adapted to rotate the crank shaft thereof, the combination of starter mechanism including a shaft having a thread formed thereon; a starter pinion threaded on the shaft adapted to be axially moved into and out of mesh with the said gear and adapted to form a rotary drive connection with the shaft when the pinion is fully meshed with the gear; and a shoulder formed in the thread of the shaft for engaging the end of the pinion thread to normally position the pinion out of engagement with the gear.

2. In a starter for use with an internal combustion engine having a gear adapted to rotate the crank shaft thereof, the combination of starter mechanism including a shaft having a thread formed thereon; a starter pinion threaded on the shaft adapted to be axially moved into and out of mesh with the said gear and adapted to form a rotary drive connection with the shaft when the pinion is fully meshed with the gear; a shoulder formed in the thread of the shaft for engaging the end of the pinion thread to normally position the pinion out of engagement with the gear; and spring means tending to maintain the pinion in engagement with the shoulder.

In a starter for use with an internal combustion engine having a gear adapted to rotate the crank shaft thereof, the combination of starter mechanism including a shaft having a long pitched thread formed there on; a starter pinion threaded on the starter shaft and adapted to be meshed with and drive the said gear to start the engine; a shoulder formed in the shaft thread, the gear being adapted, when the engine is started, to rotate the pinion relative to the shaft and move it axially thereof to engage the shoulder; and spring means tending to maintain the pinion in engagement with the shoulder, the spring also being adapted to axially move the pinion into mesh with the gear when the pinion is disengaged from the shoulder.

4-. In a starter for use with an internal combustion engine having a gear adapted to rotate the crank shaft thereof, the combina tion of starter mechanism including a shaft having a long pitched thread formed thereon; a starter pinion threaded on the starter shaft and adapted to be meshed with and drive the said gear to start the engine, the shaft thread being reduced in width to form a shoulder, the gear being adapted, when the engine is started, to rotate the pinion relative to the shaft and move it axially thereof to enga e the reduced thread on the shaft; and a spring tending to axially move the pinion towards the gear to cause the end of the pinion thread to engage the shoulder.

5. In a starter for use with an internal combustion engine having a gear adapted to rotate the crank shaft thereof, the combination of starter mechanism including a shaft having a long pitched thread formed there- H a casing secured to the shaft on; a starter pinion threaded 0n the starter shaft and adapted to be meshed with and drive the said gear to start the engine, the shaft thread being reduced in width to form a shoulder; a sleeve slidably mounted on the Shaft and counterbored to clear the thread thereof and form a shoulder adapted to engage the end of the thread to limit the axial movement of the sleeve in one direction; and having a telescopic connection with the sleeve; and a spring disposed on the shaft engaging the casing and the sleeve, the gear being adapted, When the engine is started, to rotate the pinion relative to the shaft and move it axially thereof to engage the sleeve and the shoulder on the shaft.

Signed at Toronto, of June, 1925. v

MAUN SELL B. JACKSON.

Canada, this 8th day 

